Lexus executives, when questioned in years past on the potential for an M5-fighting GS F sedan, have traditionally offered little more than "we've thought about it". Maybe a smile.

And besides the LS-based proof-of-concept vehicle built by Toyota subsidiary TMG in Germany, there's been little evidence of a large performance sedan joining the Lexus stable.

But photos snapped this week of a Lexus GS circling the Nurburgring Nordschliefe appear to confirm that yes, a GS F is coming, and yes, it's in an advanced state of development.

The bodywork is broadly similar to that of a GS 350 F Sport, but with the addition of a front chin spoiler, short side skirt extensions ahead of the rear wheels and a larger bootlip spoiler.

But the real tell-tale sign that this is something more than the average GS is the quartet of stacked exhaust pipes poking out of the rear bumper, which have been a signature feature of the IS F since its launch.

The wheels have a BBS-style mesh design and appear to be wider, though they may not be representative of the production wheel.

The larger brake package lurking behind them though are another clear indicator that this will be the performance leader of the GS range.

As for that roll cage, it's likely just there as a safety requirement for on-track testing.

At this point it's difficult to speculate on what engine might power the GS F.

The chief engineer of the 2013 Lexus IS, Junichiro Furuyama, confirmed to TMR that a new engine was under development for the next-generation IS F and upcoming RC F, but it's not clear whether this engine (which could potentially be a naturally aspirated V8 or a low-displacement twin-turbo V8) could see service in a GS F model.